Agitator impeller



Sept. 1, 1970 D. L. KlME AGITATOR IMPELLER Filed Aug. 23., 1968'//VVENTOR DONALD L. KIME W Wz,

I ATTORNEYS United States Patent O 3,526,467 AGITATOR IMPELLER Donald L.Kime, Dayton, Ohio, assignor to Chemineer, Inc., Dayton, Ohio, acorporation of Ohio Filed Aug. 23, 1968, Ser. No. 754,770 Int. Cl. B44d3/06 U.S. Cl. 416-200 4 Claims ABSTRACT OF THE DISCLOSURE An agitatorimpeller includes an upper section and a lower section each having a huband outwardly projecting blades, and the blades of both Sections arearranged to have Substantially the same path. A shaft extension projectsupwardly from the hub of the lower section through the hub of the uppersection and is threadably connected to the lower end of a drive shaft toeffect a self-tightening connection of the Sections to the shaft.

BACKGROUND OF THE INVENTION In an agitator including a prime moverconnected to drive a shaft adapted to depend into a container or tankdefining a mixing chamber, it is common to employ an impeller having aSplit hub formed in two mating sections each supporting a plurality ofeither curved or flat blades attached to the hub Sections by threadedfasteners such as ScrewS or bolts. The hub Sections are clamped togetheron the drive shaft with transversely extending screws so that theimpeller can be disassembled and in- Serted in Sections into the mixingchamber through a cover opening which is Substantially smaller indiameter than the overall diameter of the impeller. The Sections of theimpeller are re-assembled onto the drive shaft usually by inserting thehands through the opening and inserting the Screws into the hubSections.

In some agitator installations, it is not only desirable to constructthe impeller in Sections for inserting into the mixing Chamber through asmall opening, but it is also desirable to eliminate all exposedfasteners. For example, when using such an impeller in a sanitaryinstallation for mixing a food product, it is desirable to eliminateexposed fasteners and to mini'mize corner cre'vices so that the impellerdoes not collect and retain portions of the material being mixed and canbe easily cleaned. As another example, when it is necessary to providethe impeller with a coating such as a plastic or rubber coating toprevent corrosion, exposed fasteners should be avoided to providemaximum corrosion resistance and a good bond of the coating to theimpeller.

SUMMARY OF THE INVENTION The present invention is directed to animproved impeller adapted for mounting on the drive shaft of an agitatorand which provides the important features of sectional construction forinserting the impeller in Sections through a small opening, theelimination of exposed fasteners and a simplified and economicalconstruction which provides for a Self-tightening connection of theimpeller onto the drive shaft when the impeller is being driven. Inaccordance with one embodiment of the invention, the impeller includesan upper section and a lower section each having a generally cylindricalhub and a pair of diametrically opposed blades. A solid shaft extensionprojects upwardly from the hub of the lower section through the hub ofthe upper section and has an upper end portion which is threaded into ahole formed in the lower end of the drive shaft. The upper section ofthe impeller is keyed to the shaft extension to assure common rotationof the upper and lower Sections in a fixed anice nular relation, and theblades are arranged so that they each have the same path.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of animpeller constructed in accordance with the invention;

FIG. 2 is a perspective exploded view of the impeller shown in FIG. 1;

FIG. 3 is an elevational view of the impeller shown in FIGS. 1 and 2with a portion shown in axial section;

FIG. 4 is a perspective view of an impeller forming another embodimentof the invention; and

FIG. 5 is a fragmentary elevational view of the impeller shown in FIG.4.

DESCRIPTION 'OF THE PREFERRED EMB ODIMENTS Referring to the drawing,FIGS. 1-3 show one embodiment of an impeller 10 which is mounted on thelower end of an agitator drive shaft 12 having a threaded axial hole 13.The impeller 10 includes an upper section 14 and a lower section 16. Theupper section 14 has a cylindrical hub 18 with a central bore 20interrupted by an axially extending keyway 21. A pair of diametricallyopposed flat blades 25 project outwardly from the hub 18 in an axialplane, and eah blade 25 includes a downwardly and outwardly extendingportion 26 located adjacent the hub 18 so that the outer radiallyextending portions of the blades 25 are offset downwardly in relation tothe hub 18.

I The lower section 16 of the impeller 10 includes a cylindrical hub 28having an outer diameter the same as that of the hub 18 of the uppersection 14. A pair of diametrically opposed flat blades 30 projectoutwardly from the hub 28 in an axial plane and are arranged at 90 inrelation to the blades 25. Each blade 30 includes an upwardly andoutwardly projecting portion 32 adjacent the hub 28 so that the outerradially extending portions of the blades 30 are offset upwardly inrelation to the hub 28 to have the same path as the outer portions ofthe blades 25.

A cylindrical shaft extension 35 is formed integrally with the hub 28 ofthe lower section 16 and projects upwardly through the bore 20 of thehub 18. A key 36 is mounted within a groove 37 formed within the shaftextension 35 and projects into the keyway 21 within the hub 18 so thatthe upper section 14 is rigidly connected to the lower section 16 withthe blades 25 extending normally to the blades 30.

The shaft extension 35 includes a threaded upper end portion 38 which isthreaded into the hole 13 within the lower end of the drive shaft 12. Aresilient washer 40 is located between the hubs 18 and 28, and aresilient washer 42 is located between the lower end of the drive shaft12 and the upper end of the hub 18 to form fiuid tight seals between theirnpeller Sections 14 and 16 and between the drive shaft 12 and theupper impeller section 14.

Referring to FIGS. 4 and 5 which Show another embodiment of theinvention, an impeller is constructed Similar to the impeller 10 andincludes an upper section 52 and a lower section 54. The upper Section52 has a cylindrical hub 55 constructed Substantally the Same as the hub18 of the impeller 10, that is, with a cylindrical bore 56 having anaxially extending keyway 57. A pair of diametrically oposed flat blades60 are welded to the hub 55 and are pitched by an angle of approximately45 in relation to the axis of the hub 55.

The lower impeller section 54 includes a cylindrical hub having an outerdiameter the Same as the hub 55, and a shaft extension 66, constructedsubstantially the Same as the shaft extension 35, projects upwardlythrough the bore 56 of the hub 55. A key 67 secures the hub 55 to theshaft extension 66 which has an upper end portion '68 threaded into thehole 13 within the lower end of the drive shaft 12. A pair ofdiametrically opposed flat blades 70 are welded to the hub 65 of thelower section 54 and are ptched at the same angle as the blades 60 ofthe upper section 52. Thus the outer configuration of the lower impellersection 54 is substantially identical to that of the upper section 52.

As shown in FIG. 5, the blades `60 extend downwardly in relation to thehub 55, and the blades 70 extend upwardly in relation to the hub 65 Sothat each of the blades 60 and 70 have the same path when the shaft 12is rotated. Resilient washers 72 and 74 are mounted on the shaftextension 66 in the same manner as the washers 40 and 42 to form a fluidtight seal between the hubs 55 and 65 and between the lower end of theshaft 12 of the hub 55.

From the drawing and the above description, it is apparent that animpeller constructed in accordance with the invention provides desirablefeatures and advantages. For example, by forming the shaft extension 35as part of the lower section 16 of the impeller and by extending theshaft extension 35 upwardly through the hub of the upper section 14 forthreading into the hole 13, a self-tightening connection is formedbetween the impeller 10 and the drive shaft 12 when right hand threadsare used and the shaft 12 is driven in the direction of the arrow shownin FIG. 1. The construction of the impeller 50 forms a similarself-tightening connection. Furthermore, the assembly of the impeller 10or the impeller 50 onto the drive shaft 12 can be performed quickly andwithout the use of exposed fasteners, which is especially desirable Whenthe upper and lower Sections of the impeller are coated with a plasticor rubber coating or when the impeller is used in a sanitaryinstallation for mixing a food product.

The impeller construction of the invention also provides for insertingand assembling of the impeller through a circular opening having adiameter substantially smaller than the overall diameter of theimpeller. That is, each section of the impeller can be insertedseparately through the opening and then be conveniently and quicklyassembled onto the end of the drive shaft 12. The impeller constructionalso provides for minimizing the outer diameter of the hub of the upperand lower Sections which is desirable not only from an economicalstandpoint but also for obtaining optimum performance.

Another important advantage is provided by the offset relation of theblades 25 and 30 or the blades 60 and 70 in relation to theircorresponding supporting hubs. That is, by extending the upper bladesdownwardly and the lower blades upwardly so that all blades have thesame path, the impeller is provided with a balance construction which isimportant for eliminating any significant vibration within the agitator.Furthermore, the common path of all of the blades enables the use ofperformance charts for conventional impellers to predict the performanceof an impeller constructed in accordance with the invention.

While the two impeller embodiments of the invention illustrated in thedrawing each employ a set of flat blades, it is to be understood that itis within the scope of the invention to provide each impeller sectionwith a set of curved blades according to the particular mixing actiondesired from impeller. It is also within the scope of the invention toform the stud shaft 35 as an integral portion of the drive shaft 12 andthread the shaft 35 into the hub 28 of the lower impeller section 16.Furthermore, it is within the scope of the invention to extend the shaft35 and to mount one or more intermediate impeller sections, similar tothe section 14, on the extended shaft to effect additional agitation.

While the forms of apparatus herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to these precise forms of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. An improved impeller adapted for convenient mounting on an agitatordrive shaft, comprising a lower section and an upper section eachincluding a hub and blade means projecting outwardly from said hub,means defining an opening within said hub of said upper section, a shaftextension rigidly secured to said hub of said lower section andextending upwardly through said opening within said hub of said uppersection, key means for rigidly connecting said hub of said upper sectionto said hub of said lower section to effect positive common rotation ofsaid sections, said shaft extension including an upper end portionprojecting above said hub of said upper section, and said upper endportion having external threads for engaging a threaded hole formedwithin the lower end of said drive shaft to effect a positiveself-tightening connection of said Sections to said drive shaft inresponse to relative rotation between said Sections and said driveshaft.

2. An impeller as defined in claim 1 wherein said blade means of eachsaid section comprise a pair of diametrically opposed substantially flatblades, said blades of said Sections are offset axially of theircorresponding said hubs and are disposed in interfitting relationcausing all of said blades to have substantially the same path, and saidhubs have a combined axial length substantially no greater than thewidth of said blades in an axial direction.

3. An impeller as defined in claim 1 wherein said blade means of eachsaid section comprise a pair of diametrically opposite substantiallycoplanar blades.

4. An improved impeller adapted for convenient mounting on an agitatordrive shaft, comprising a lower section and an upper Section eachincluding a generally cylindrcal hub and at least one substantially fiatblade projecting outwardly from said hub, said blades of said upper andlower Sections being offset axially of their corresponding said hubs andbeing disposed in interfitting relation causing all of said blades tohave substantially the same rotational path, said hubs having a combinedaxial length substantially no greater than the width of said blades inan axial direction. A shaft extension rigidly connected to said hub ofsaid lower section and projecting upwardly therefrom, means defining anopening within said hub of said upper section for receiving said shaftextension, key means for rigidly connecting Said hub of said uppersection to said hub of said lower section to provide for positive commonrotation of said upper and lower sections in fixed angular relation,said shaft extension including an upper end portion projecting abovesaid hub of said upper section, and said upper end portion havingexternal threads for engaging a threaded hole within the lower end ofthe drive shaft to effect a self-tightening connection of said Sectionsto said shaft in response to relative rotation between said Sections andsaid drive shaft.

References Cited UNITED STATES PATENTS 1,519,533 12/1924 Dingle 259-1342,172,72l 9/1939 Wigzell -171 X 2,589,558 3/1952 Lamoreaux 259-1342,811,339 10/1957 Osborne et al. 259-134 3,294,365 12/ 1966 Wilde et al.170-165 X EVERETTE A. POWELL, JR., Primary Examiner

